1. Field of the Invention
The present invention relates in general to pumps for material conveyance. In particular, the present invention relates to an improved conveyance pump providing a substantially constant output pressure.
2. Description of the Related Art
For the conveyance of flowable materials, such as granular material, liquid material, and liquid material containing solid elements, and gasses, it is know to provide various pump arrangements. One typical example is the use of a rotating auger within an exterior sleeve. A feed hopper or input pipe leads to a first end of the auger sleeve, and the rotating helical lands of the auger move the material to the second end of the sleeve to an exit opening. The constantly rotating auger may thus be employed to maintain a pressure upon the output flow, assuming there is some restriction upon the output flow downstream of the auger exit.
Such pressurization is employed in many fields of endeavor, including the production of food for human consumption. For example, solid food bits, such as cut carrots or other material, may be conveyed with a certain amount of water and steam at high pressure to effect sterilization of the food items. It is important to maintain the pressure on the product to ensure penetration of the steam and full sterilization.
However, it is often the case that such an auger pump will be employed to provide a pressurized flow to a downstream operation which is not entirely continuous. For example, there may be occasional product flow stoppages due to an intermittent downstream process, jamming of the product within the output conduit, etc. While the downstream flow of the product may be interrupted, the auger pump continues to operate, forcing additional product into the output conduit, thus raising the pressure within the output conduit.
For those situations or processes where a constant output pressure, or at least a maximum desired output pressure, are desired, it would be necessary to place a pressure sensor within the output conduit and have this pressure sensor operatively connected to the control system of the auger. Such an arrangement is expensive, not particularly reliable, and provides pressure fluctuations within the output conduit.